1. Field of the Invention
The present invention relates to a holder for use with a disposable pre-filled syringe cartridge. More particularly, the present invention relates to a syringe barrel having a safety sleeve to prevent accidental needle sticks and abuse of the syringe.
2. State of the Art
Accidental needle sticks have long been a problem in the medical profession. They most often occur during the recapping of a contaminated needle or immediately after use and prior to safe disposal. Such needle sticks place the medical professional (clinician) at great risk. When needles are not recapped, additional needle sticks are caused by uncapped needles found in patient beds, linens, and in garbage cans, and place health care, housekeeping and sanitation personnel at risk. Because accidental needle sticks can now result in deadly incurable diseases as well as the previously appreciated serious, but curable diseases, the need for eliminating the needle stick problem has reached extreme urgency. In addressing the urgency, many devices have been proposed. Indeed, the prior art discloses a number of devices which are arranged to shield the needle of the syringe after use.
Safety-needled syringes are disclosed in U.S. Pat. Nos. 2,571,653 to Bastien, 4,026,287 to Haller, 4,425,120 to Sampson et al., 4,573,967 to Sampson et al., 4,631,057 to Mitchell et al., 4,643,199 to Jennings, Jr. et al., 4,655,751 to Harbaugh, 4,666,435 to Braginetz, 4,681,567 to Masters et al., 4,702,738 to Spencer, and 5,059,185 to Ryan. Most of these devices involve some kind of sleeve which slides into a locked position to cover the needle of the syringe. Some of the devices are quite complex and difficult to manufacture and some of the devices do not operate so well as to effectively lock the sleeve into position covering the needle.
In U.S. Pat. No. 4,425,120 to Sampson et al., for example, a complex arrangement of tracks including axial and circumferential components of shield and syringe members are required, making manufacture and assembly more difficult and expensive. Moreover, the sleeve which guards the needle is releasable from the safety position which is undesirable. It is preferred that the sleeve be locked in the safety position so that it is not inadvertently removed leaving the needle exposed. U.S. Pat. No. 4,631,057 to Mitchell et al. requires a collar member over which a shield slides. The device is complex, difficult to manufacture and assemble, and requires permanent attachment of the collar to the syringe tube. U.S. Pat. No. 4,573,967 to Sampson et al. requires additional intricate members which are attached to both the tube and the shield and which provide a locking action. The additional members are expensive to manufacture and assemble, unwieldy to handle, and would require a clinician to develop a new technique for utilization.
U.S. Pat. No. 4,655,751 to Harbaugh requires at least one slide groove to maintain the shield in the proper rotational axis and to thereby align a pair of ears on the shield with either one of two pairs of pockets in the outer surface of the syringe tube. Besides being relatively expensive to manufacture and assemble due to the ears and pockets, it also requires flexing of the shield to move it to the needle-shielding position, and thus has the potential for cracking or breaking. Moreover, the sleeve which guards the needle is releasable from the safety position which is undesirable. Similarly U.S. Pat. No. 4,681,567 to Masters et al. requires slide grooves in the shield and knobs or ears on the tube. Restrictions in the groove provide locking positions for the shield. Again, however, the knobs may be costly to manufacture and assemble and are prone to breaking. Also, it is not evident how such a device could be manufactured without sonically welding the shield around the tube, as any attempt to slide the shield over the tube and into a non-extended position would require overcoming the same locking action which is used to finally lock the shield relative to the tube.
U.S. Pat. No. 4,666,435 to Braginetz requires a complex and difficult to manufacture arrangement of tracks, rails, detents and stop surfaces which involves considerable expense to manufacture and assemble. Moreover, to lock the syringe tube and shield, the user must step through a predetermined sequence of relative rotational and longitudinal movements between the shield and the syringe tube. U.S. Pat. No. 2,571,653 to Bastien is simpler in design and has a single latch secured by a tensioning device to lock the shield at fixed points on the syringe tube, but the shield is not as secure in the safety position due to the single latch and any mishandling of the device could cause movement of the tensioning device and exposure of the needle.
U.S. Pat. No. 4,702,738 to Spencer shows a syringe with a pair of longitudinal grooves coupled by a circumferential groove and a shield having a protrusion or boss on its inner surface. The shield is mounted on the tube by engaging the boss in one of the longitudinal grooves and sliding the shield until the boss engages the circumferential groove. Rotating the shield allows the boss to engage the second longitudinal groove. The grooves are provided with cavities at different points wherein the boss my extend and somewhat lock the shield in a position and preferably in a locked position when the shield is extended over the needle. The grooves, boss, and cavities taught by Spencer, however, are schematic in nature and do not assure smooth and positive operation of the device.
U.S. Pat. Nos. 4,026,287 to Haller and 4,643,199 to Jennings, Jr. et al. show safety devices which utilize a technique of withdrawing the needle into the tube in order to render the needle harmless. These devices, and others like them typically require additional parts and are difficult to manufacture.
In recent years, pre-filled disposable syringe cartridges have been widely used. These syringes 10, as shown in prior art FIG. 1a, comprise a pre-filled ampoule 11 with an attached distal needle 12 (having a removable needle guard 13) and a proximal inserted rubber seal 14 having a threaded insert 16. Typically, the needle 12 is double pointed and mounted in a needle hub 18 covering a membrane seal on the ampoule. The pre-filled syringe 10 is inserted into a reusable holder 20, as shown in prior art FIGS. 1b and 1c, comprising a barrel 22 and a plunger rod 24. After insertion into the barrel 22, a locking screw 26 advances the syringe forward until shoulders 28 of the barrel engage the needle hub 18 and force the needle 12 towards the membrane seal thereby opening fluid communication between the needle 12 and the ampoule 11 and securing the syringe within the barrel 22. The plunger rod 24 is then threaded to the threaded insert 16 on the rubber plunger 14 of the ampoule 11 and movement of the plunger forward causes movement of the threaded insert 16 and the injection into the patient of the fluid in the ampoule.
As noted above, the needle guard 13 on pre-filled disposable syringe cartridges is simply a removable cap which frictionally engages the needle hub 18. Moreover, the known reusable holders for pre-filled syringe cartridges provide no safety means for covering the needle as it is expected that once the syringe is emptied, the needle will be recapped and the syringe removed from the reusable holder. Unfortunately, it is during this recapping and removal of the syringe that the danger of needle sticks is the greatest.
U.S. Pat. No. 5,059,185 addresses the use of safety shields for needled devices generally and includes a safety means for use with pre-filled disposable syringe cartridges. This earlier patent does not, however, deal in depth with the specific problems encountered with the use of pre-filled disposable syringe cartridges.